Dry Rotary Swaging with Structured Tools

AbstractRotary swaging is a cold bulk forming process. The diameter of the workpiece is reduced incrementally by oscillating movement of the tools. The established processes use lubricants which fulfill necessary functions such as lubricating, cooling and cleaning of the tools. Disadvantages caused by the use of lubricant are costs of recycling, replacement of lost coolant and for the cleaning of the workpiece. To eliminate the lubricant it is necessary to substitute the functions of the lubricant in other ways. For example by means of coating and structuring of the tools.In this study infeed rotary swaging with structured tools is investigated using finite element simulations. Different structures are implemented in the reduction zone of the tools. The influence is investigated by the radial and axial process forces. Additionally first structured tools are manufactured and experimentally tested. The results of modeling and testing are discussed

Hierarchical distributed scenario-based model predictive control of interconnected microgrids

Microgrids are autonomous clusters of generators, storage units and loads. Special requirements arise in interconnected operation: control schemes that do not require individual microgrids to disclose data about their internal structure and operating objectives are preferred for privacy reasons. Moreover, a safe and economically meaningful operation shall be achieved in presence of uncertain load and weather-dependent availability of renewable infeed. In this paper, we propose a distributed model predictive control approach that satisfies these requirements. Specifically, we demonstrate that costs and safety of supply can be improved through a scenario-based stochastic control scheme. In a numerical case study, our approach is compared to a certainty equivalence scheme. The results illustrate the improved safety and reduced runtime costs as well as sufficiently fast convergence

Bounded rationality and valuation

A computational valuation model is developed to predict discrepancies between choices and valuations in economic experiments. The model is based on Boundedly Rational Expected Utility Theory (Navarro-Martinez et al., 2017) and predicts average certainty equivalents for monetary lotteries that are higher than choices would imply from the same set of underlying preferences. Thereby, the model predicts the preference reversal phenomenon (Slovic and Lichtenstein, 1968). The model predicts that a choice between a lottery and a sure payoff can influence a subsequent money valuation of the choice’s strength of preference. This monetary strength of preference (MSoP), can be positively affected by spill-over effects from the choice process and also by consistency-seeking behaviour towards information about the choice. This can explain observations by Butler et al. (2014a) that participants systematically state MSoP values that are too high relative to their choices. Model simulations show how this model differs from existing computational valuation models. When adapted to predict MSoP values, these instead predict a negative MSoP mismatch. These predictions are tested in a laboratory experiment, which finds a positive MSoP mismatch but only when MSoP values stem from upward adjustments to a sure amount. When sure amounts are adjusted downwards, a negative MSoP mismatch occurs instead. Neither the novel model nor existing theory can explain this two-fold pattern. Controlling for the delay between choices and MSoP valuations also rules out the possibility of spill-over effects. Participants also value lotteries too high relative to their choice behaviour. Contrary to theory, a reaction time analysis shows that individually-longer reaction times do not reduce discrepancies between valuations and choice data. Preference reversals do not become less frequent when participants deliberate for longer. Altogether, these results show novel and yet unexplained phenomena in valuation behaviour but also highlight how theory needs to be adapted to explain these

Rapid Auxin-Induced Cell Expansion and Gene Expression: A Four-Decade-Old Question Revisited

The classical effect of the plant hormone auxin is very rapid stimulation of cell expansion followed by sustained growth over a longer time period. However, auxins are also important in other responses, such as cell division and differentiation. Recently, the TRANSPORT INHIBITOR RESPONSE1/AUXIN

Nicht wendendes Bodenbearbeitungssystem im Ökologischen Landbau-Dammkultursystem "Turiel

In dem interdisziplinären Forschungsprojekt wurde ein Exaktversuch für Systeme der reduzierten Bodenbearbeitung im Ökologischen Landbau eingerichtet. Verglichen werden das Dammkultursystem (DKS) nach Turiel-Major und das Ecomat-System der Firma Kverneland mit dem herkömmlichen Pflugsystem, jeweils im Kontext entsprechend angepasster Anbauverfahren. Im Rahmen des Projektes wurden auf der Hessischen Staatsdomäne Frankenhausen, dem Lehr- und Transferzentrum des Fachbereichs Ökologische Agrarwissenschaften der Universität Kassel, zwei Workshops durchgeführt. Durch den regelmäßigen Kontakt mit Landwirten, Beratern, Entwicklern und Wissenschaftlern wurde und wird Praxiswissen in die Bearbeitung wissenschaftlicher Fragestellungen einfließen. Der Wissenstransfer in beiden Richtungen wurde und wird intensiviert und vorangetrieben. Es handelt sich um einen Bodenbearbeitungssystemversuch im ersten Versuchsjahr. Insofern sind die Ergebnisse nicht geeignet, die Systeme zur Bodenbearbeitung in ihrer Gesamtheit zu bewerten. Der Systemwechsel zum Ecomat ist einfach zu bewerkstelligen. Die Veränderungen zum Standard-Pflugsystem sind gering. Die Vorzüge des Ecomat-Systems liegen in seiner hohen Schlagkraft. Durch die geringe Bearbeitungstiefe ist der Zugkraftbedarf gering. Bei 3 m Arbeitsbreite und Fahrgeschwindigkeiten von 9-12 km/h werden Flächenleistungen bis zu 2,5 ha/h erreicht. Das Ecomat-System hatte im Umstellungsjahr keine nachteiligen Auswirkungen auf die Erträge. Die N-Mineralisation verlief wie beim Pflugsystem. Bei der Umstellung auf DKS ist die Dammbreite (75 oder 90 cm) der Arbeitsbreite und der Pflanz- und Erntetechnik anzupassen. Das DKS nach Turiel-Major zeichnet sich gegenüber anderen DKS durch seine hohe Flexibilität und Arbeitsbreiten bis zu 7,2 m aus. Eine Systemumstellung nach der Ernte zur Herbstbestellung ist sinnvoller als im Frühjahr. Die Erträge bei Umstellung auf das DKS waren bei der extrem trockenen Witterung im Frühjahr geringer als bei den Pflugsystemen. Sie erlauben daher keine allgemeingültige Bewertung des DKS, da sich die Veränderungen der Bodenstruktur erst nach mehreren Jahren stabilisieren werden

Synergistic approaches to ultra-precision high performance cutting

Diamond milling allows for the flexible production of optical and high precision parts, but suffers from poor setup and production speeds. This paper presents recent advances that aim towards achieving high performance (HPC) and high speed cutting (HSC) in ultra-precision machining. After a short introduction, the benefits of high speed cutting for both metals and brittle-hard materials are shown. Thereafter, novel mechatronic devices are presented that enable an automated balancing of the applied air bearing spindles and the application of multiple diamond tools on one tool holder and by thus, contribute to HPC. These developments are supplemented by a novel linear guiding system based on electromagnatic levitation that, along with a dedicated model-based control system, enables fast and precise movements of the machine tool. After presenting the recent developments in detail, their synergistic performance is assessed and an outlook to future developments is given. © 2020 The Author

Development of a smartphone virtual reality game to support the radiation therapy of children and adolescents in proton centers

IntroductionFor most patients, cancer therapy with radiation is a new experience coming with many unknown challenges. This can be stressful, particularly for children and adolescents. With the aim of reducing this stress and anxiety, a virtual-reality (VR) game, which can be used by patients prior to treatment, was developed and evaluated in a proton therapy center.MethodsThe specifications were derived from literature and from interviews with medical staff and patients. The gantry including the sound of its moving components and the sound of the interlock and safety system were identified as the main features relevant for preparation of a radiation course. Potential implementation difficulties were identified in a literature study and regarded in the design. Within the VR game, patients could interact with modeled equipment of the treatment room and hear the reportedly stress-inducing sounds in a stress-free environment prior to the treatment. The VR game was evaluated in a second series of interviews with patients.Results and DiscussionThis exploratory study demonstrated the specification, implementation and safe application of a VR game dedicated to young proton therapy patients. Initial anecdotal evidence suggested that the VR gaming experience was well received and found to be helpful when preparing young patients for radiation therapy

Eradication of Acinetobacter baumannii/Enterobacter cloacae complex in an open proximal tibial fracture and closed drop foot correction with a multidisciplinary approach using the Taylor Spatial Frame®

Background Multi-drug-resistant bacteria (e.g. Carbapenem-resistant Acinetobacter baumannii, extended-spectrum betalactamase or carbapenemase-producing enterobacteriaceae) are emerging in early-onset infections. So far, there is no report describing the eradication of these bacteria in a osseous infection of an open proximal tibial fracture in combination with the hexapod technology to address both osseous consolidation and closed drop foot correction. Case presentation After sustaining a proximal tibial fracture (Gustilo 3B), a 41-year-old man was primarily treated with open reduction and internal fixation by a locking plate and split-thickness skin graft in the home country. At the time of admission to our hospital there was a significant anterolateral soft tissue defect covered with an already-necrotic split-thickness graft and suspicious secretion. CAT and MRI scans revealed no signs of osseous healing, intramedullary distinctive osteomyelitis, as well as a large abscess zone in the dorsal compartment. Multiple wound smears showed multi-drug-resistant bacteria: Acinetobacter baumannii (Carbapenem resistant) as well as Enterobacter cloacae complex (AmpC overexpression). After implant removal, excessive osseous and intramedullary debridements using the Reamer Irrigator Aspirator (RIA®) as well as initial negative pressure wound therapy were performed. Colistin hand-modelled chains and sticks were applied topically as well as an adjusted systemic antibiotic scheme was applied. After repetitive surgical interventions, the smears showed bacterial eradication and the patient underwent soft tissue reconstruction with a free vascularized latissimus dorsi muscle flap. External fixation was converted to a hexapod fixator (TSF®) to correct primary varus displacement, axial assignment and secure osseous healing. A second ring was mounted to address the fixed drop foot in a closed fashion without further intervention. At final follow-up, 12 months after trauma, the patient showed good functional recovery with osseous healing, intact soft tissue with satisfactory cosmetics and no signs of reinfection. Conclusions A multidisciplinary approach with orthopaedic surgeons for debridement, planning and establishing osseous and joint correction and consolidation, plastic surgeons for microvascular muscle flaps for soft tissue defect coverage as well as clinical microbiologists for the optimized anti-infective treatment is essential in these challenging rare cases